Electronic devices typically include one or more components that are formed from semiconductor wafers. The semiconductor wafers include a number of transistors, sometimes on the order of thousands of transistors up to billions of transistors, to accomplish the functions of the electronic devices. In some cases, electronic device designers often attempt to improve the performance of electronic devices and/or increase the functionality of electronic devices while reducing cost, by adding more transistors to semiconductor wafers.
Semiconductor device manufacturers have responded by continuing to decrease the size of the transistors formed on the semiconductor wafers. However, the extent of the decrease in size of the transistors may be limited due to limitations of processes used to form certain components of the transistor. For example, the decrease in size of the p-type or n-type junctions of a transistor may be limited due to the ability of semiconductor manufacturers to effectively dope semiconductor wafers such that the concentration of the dopant in the semiconductor wafer is uniform and at a shallow enough depth to support a smaller junction size.
In particular, as the need for the depth of junctions of transistors to decrease below the 14 nm mark has increased and as transistors have been formed in three-dimensional shapes (e.g. finFETs), semiconductor manufacturers have encountered problems forming properly doped junctions and source/drain extensions, when using traditional doping methods, such as ion implantation. For example, ion implantation of dopants can damage the surface of the substrates, which affects the performance of the junction. Ion implantation may also suffer from limited lateral diffusion control resulting in greater short channel effects which decrease transistor performance. Additionally, since ion implantation is a line of sight doping technique, as the features of three-dimensional transistors decreases, the ion implantation devices are unable to access the entire surface of the substrate, which leads to a non-uniform doping of the substrate surface. When the junctions of transistors included in electronic devices are not uniformly doped, the performance of electronic devices including these transistors can decrease due to the inability of the transistors to signal discrete on and off states.